The transcription and translation machinery is of vital importance for cell growth. In Escherichia coli the synthesis of ribosomes, RNA polymerase and many other components of the transcription and translation apparatus is regulated in response to changes in the growth medium. My ultimate goal is to understand the molecular details of the mechanisms underlying this regulation. The information gained by this study should contribute to our understanding of the molecular basis for regulation of cell growth. The genes for the E. coli ribosomal proteins (r-proteins) are organized into at least 16 transcription units. These genes and the genes for rRNA are regulated coordinately. Autogenous regulation, whereby unique r-proteins regulate the expression of their own operons, provides one mechanism by which the cell regulates the ribosome synthesis. To obtain more information about the molecular details of this process we will study transcription and translation during the autogenous inhibition of r-protein synthesis. We will also investigate the interaction between the regulatory r-protein and its mRNA by biochemical and genetic methods. We have preliminary evidence for an additional mechanism affecting the expression of r-protein genes. We will characterize this regulation by gene dosage experiments and by introducing mutations into specific r-protein genes. The overall regulation of ribosome synthesis is probably achieved by a complex interaction between several different mechanisms. We will try to identify these mechanisms and to assess their relative contributions to ribosome synthesis. To accomplish this, we will dissect a r-protein operon genetically, for example, by substituting a non-ribosomal promoter for the natural r-protein promoter and by introducing mutations in the leader sequence. The regulation of such modified operons will be studied. Finally, we will study the regulation of elongation factor Tu. This is a particular interesting protein because it is one of the most abundant proteins in the cell and it is encoded by two genes mapping at different locations of the chromosome.